The 1999 1 oz.t version was minted by 3 different mint - Shanghai Mint, Shenzhen Guobao Mint, Shenyang Mint, hence resulted in 3 different types of fonts for the mint year '1999'. The different fonts are as follows for each mint:

Small Date - Shanghai Mint;

Large Date - Shenyang Mint;

Serif Date - Shenzhen Guobao Mint.

As seen below, the Serif Date is the most scarce version of the three and in my opinion the most scarce of the series. Though its price is lower than the 2000 Mirrored version, the 1999 Serif Date version is seldom seen on ebay as double-sealed, usually they would have been graded.

The year 1999 is the last year that the 1 oz.t Proof version was issued. No data was recorded for this as I'm not keen on coloured coins at all.